The subject matter disclosed herein relates generally to cellular communication systems, and more particularly, to a system for assigning communication cells to servers within a cellular communication system.
Cellular communication systems are used to provide voice and data communications between one or more communication units within the cellular communication system. The cellular communication units, for example, cellular telephones, mobile radios or other cellular devices allow communication between one or more users. A communication link may be established between two mobile cellular phone users allowing voice communications over the established communication link. The communication link may be provided using the Global System for Mobile Communications (GSM) standard that allows communication between different mobile telephones or radios.
Cellular data systems are also known that provide packet data communication capabilities that allow communication of voice and data. For example, the General Packet Radio Service (GPRS) standard may be used to communicate voice or other data in packets over a data channel. The voice and data may be communicated over a shared data channel. As another example, the Enhanced Data Rates for GSM Evolution (EDGE) standard may be used to provide higher speed data transmissions for particular applications.
In these different cellular communication systems, individual users may be able to communicate with a plurality of other users via a group call or other group connection. For example, in the Open Mobile Alliance (OMA) standard, users with mobile devices may communicate using a push-to-talk function, referred to as a push-to-talk over cellular (POC) function that allows users to communicate with different groups within a cellular communication system. Users may establish personal group lists or “buddy” lists on a cellular telephone and upon depressing a single button a user is able to establish a connection and communicate with or broadcast a message to multiple users. The multiple users may have been alerted to a request to join the connection.
The communications between devices corresponding to the personal group lists or “buddy” lists typically include small numbers of users or subscribers and the voice or data that is communicated is typically not time critical. If the particular cellular communication coverage area or communication cell in which a group communication is occurring becomes overloaded such that the capacity is exceeded (e.g., bandwidth exceeded) and some of the participants in the group call are unable to connect to the communication link (or some are dropped), those members of the group will not be able to participate in the communications. Thus, some group members will not be able to listen to the message or obtain the data transmitted over the group connection. However, because this type of personal communication is often not time critical, there are minimal consequences or no serious consequences resulting from such loss of connection or inability to connect by some users or subscribers. In other types of communication such as emergency group calls, loss of connection or inability to connect to a call can have serious (sometimes life threatening) consequences.
A main voice server typically controls a plurality of local voice servers corresponding to a plurality of local access points. The main voice server assigns coverage areas or cells to the local voice servers to manage the wireless capacity. The local voice servers can become overloaded as new users enter a communication cell already having users communicating therein and assigned to the same local voice server. Accordingly, communication traffic between users can cause large amounts of traffic between servers, which can affect overall system performance. Thus, because users are not always in the same cell with other users with which the users are communicating, inter-server communications can overload the system. Moreover, the local voice servers are unaware of the network topology, namely where the cells are located, thereby making it even more difficult to minimize inter-server traffic.